1. Field of the Invention
The present invention relates to a safety gas controlling system and more particularly to a safety gas controlling system which can stabilize the inner gas pressure and also minimize the amount of residual gas contained by efficiently utilizing the gas in the container.
2. Description of the Prior Art
In manufacturing semi-conductor devices, a safe delivery source cylinder (SDSC) is generally used to reserve poisonous and corrosive gases such as boron fluoride (BF3), hydrogen phosphate (PH3), and hydrogen arsenate (As H3) which are injected into cylinder in vacuum state for use in an ion implantation source. Furthermore, in the conventional technique, a pressure difference between inner and outer gas pressures of a cylinder is used to deliver the gas in a cylinder for ion implantation. For example, when a SDSC is full of a gas with a pressure which is larger than the pressure in an ion implantation source, the gas reserved in the SDSC may flow into the vacuum ion implantation source by way of a gas transmitting device. But until the amount of residual gas in the SDSC is decreased to 30% of its initial amount, it is hard to deliver the gas any more from the SDSC. This residual gas can not be used and results in waste of material.
In order to improve the above described shortcomings existing in the conventional SDSC's, the inventor of the present invention has succeeded in developing a safety gas controlling system through a long term study, and it is now will be disclosed herein below.